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Finding the Fourth Proportional to 81.72, 112.78 and 47.22

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Solution

The fourth proportional to 81.72, 112.78 and 47.22 is: 65.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.72 : 112.78 = 47.22 : x
  2. Step 2: Convert to fraction form
    81.72/112.78 = 47.22/x
  3. Step 3: Cross multiply
    81.72x = 112.78 × 47.22
  4. Step 4: Simplify right side
    81.72x = 5,325.42
  5. Step 5: Solve for x
    x = 5,325.42/81.72
  6. Step 6: Final answer
    x = 65.17

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.